The standard library should provide a way to encode data using the
standard multipart/form-data encoding.

This encoding is required to support file uploads via HTTP POST (or PUT)
requests.

Ideally file data could be streamed to the remote server if httplib
supported iterable request bodies (see issue #3243).

Mailing list thread:
http://mail.python.org/pipermail/python-dev/2008-June/080783.html

see http://code.activestate.com/recipes/146306/ for a user contributed
implementation.

I also wrote some software to handle this:
http://atlee.ca/software/poster/poster.encode.html

The reason I wrote this is to avoid having the load the entire file into
memory before posting the request.

This, along with Issue #3243, would allow streaming uploads of files via
HTTP POST.

So, what is the best way to go about this (beyond docs and tests)? Beat
the linked recipe into a patch, adapt Chris' implementation?

Once upon a time I wrote a library that did some of this among other things:

http://code.google.com/p/urllib3/

Or specifically:
http://code.google.com/p/urllib3/source/browse/trunk/urllib3/filepost.py

The code was borrowed from some of the recipes mentioned, but cleaned up
and adjusted a bit. Feel free to use it or borrow from it in any way you
like.

This request really does need a patch+tests+doc changes - I don't know if 
anyone with +commit has the time to distill the various implementations 
and generate something.

Daniel suggested marking this as superseding issue 727898, and I agree.  But I want to note that in that issue Barry suggested that it was possible services from the email package could be useful in building this support, and that there might be a better place for it to live than urllib.